This invention relates to a dampener element that is permeable to fluid flow. In particular, this invention relates to a dampener permeable to fluid flow placed in a fluid tank of a motor vehicle.
Sloshing noises that originate inside a fluid tank of a motor vehicle, such as a fuel tank, can be perceived as annoying. These noises are due to the movement of liquid fuel during driving. Dampener or baffle elements used to prevent or reduce sloshing noises in the fuel tank are known in various designs. From German patent specification DE 196 50 415 C2, it is known to locate inside a fuel tank dampener elements that float on the fuel surface. These dampener elements have a freely floating element whose surface is equipped with a material, for instance knitted fabric that has open pores. Several such elements may be freely floating in the fuel tank, and are not necessarily connected to each other. These dampener elements obstruct waves and currents in the tank and act directly as noise dampeners.
Different embodiments of plate-shaped and tubular baffle elements are known from German patent specification DE 39 05 611 C2 and its foreign equivalent, U.S. Pat. No. 4,974,743. Baffle elements are particularly located at the interior walls of the fuel tank and are intended to cause a reduction of the energy of the impinging fuel waves and thereby reduce impact noise. One embodiment of the baffle element consists of a corrugated plastic sheet molded with numerous slits which, when expanded, form meshes that serve as voids to entrap air. The entrapped air effectively dissipates the energy of the waves, so that the impact force of the fuel contacting the tank walls is dramatically decreased, thus suppressing the noise level. In another embodiment, the baffle is formed from a bent sheet with one side having a large number of plastic needles, similar to a brush, with the needles facing the fuel flow. Yet another embodiment in this specification discloses a baffle consisting of a sheet made from a large number of synthetic resin or plastic fibers that are mixed and entangled with one another, forming numerous energy dissipating voids.
A further variation of a dampener element is known from U.S. Pat. No. 4,844,278. In this disclosure, the interior walls of the fuel tank are equipped with a three-dimensional structured plastic insert whose structure forms small calming chambers. The wave fronts of the sloshing fuel impact the fuel-free regions of the tank insert and are dissolved by the calming chambers into a plurality of wave sections over a large area. Guide fins are further provided to divert the wave fronts and improve the dampening effect by increasing the length of the flow paths.
Furthermore, it is also known that, when the fuel level in the tank drops, not only does the amplitude of the waves causing the sloshing noise increase, but the resonance volume in the fuel tank also increases, which causes the sloshing noise to become particularly loud. Baffles which are attached as impact elements at interior walls would have to cover nearly the entire fuel tank surface in order to be effective everywhere. This approach is cumbersome, work-intensive and expensive. Floating dampener elements, as known from the afore-mentioned DE 196 50 416 C2, have a less complicated design and can be accommodated in fuel tanks with varying shapes if necessary. However, they also require a relatively large amount of space to be effective, which unnecessarily restricts the filling capacity of the fuel tank.
An object of the present invention is to provide dampener elements which largely prevent potential waves of liquid fuel from forming, have a simple and robust design, can be manufactured cost-effectively, and can be accommodated simply, while not restricting the filling capacity of the fuel tank. A further object is to provide a fuel tank equipped with said dampener elements that has a very low noise level.
Other objects and advantages of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
According to the present invention, there is provided a dampener assembly including a dampener element that has the form of a lattice, mesh, or similar network. The dampener assembly is meant to be attached with a horizontal orientation inside a fluid tank of a motor vehicle, such as a fuel tank or the like. Preferably the dampener assembly is attached adjacent a bottom portion of the tank.
A dampener assembly according to this invention that has been placed inside a liquid fuel tank is particularly effective in preventing the creation and propagation of large-volume waves, particularly during acceleration or deceleration of the vehicle, as well as, in the case of a depleting fuel volume, which can create sloshing noises at the interior walls of the fuel tank. In particular, this dampening can be attributed to the lattice or mesh design. Further, this design is very simple and can be produced easily. Since the dampener is located relatively close to the bottom of the fuel tank, the filling quantity of the tank is not restricted, unlike some prior art approaches. Since waves in liquids are not a superficial occurrence but reach deep into the liquid, the motion-restricting device, which is located near the bottom of the fuel tank, causes an obstruction during the origin of the wave and a quick dampening of possible fuel movement, even when the level of the fuel is higher.
The dampener element is preferably formed of a material that provides dimensional stability. The dampener element includes a plurality of adjoining base elements. The base elements include connection bars that converge at junction points. Preferably, each base element forms a polygon. The dampener element can be formed from plastic, in particularly by injection molding.
In a preferred embodiment, the base elements each have the same shape. Still more preferably, each base element is square shaped. Such a consistently designed dampener assembly is able to effectively dampen fluid movement in the tank in all possible directions.
Because the dampener assembly is subject to frequent loading and unloading of fluid forces, it is preferable for durability reasons that the dampener assembly be resilient. In particular, it is desirable that the dampener assembly is designed having an elastic deformation limit greater than the fluid forces to which it is subjected. A preferred embodiment of a dampener assembly having a resilient structure includes a dampener element having connection bars that are joined by junction points that are hollow, such as a such as a ring, sleeve or the like.
In a preferred embodiment, the dampener assembly can be attached in a simple and durable manner inside the fuel tank by having at least one of the junction points include a hollow sleeve that is adapted to slide about and into locking engagement with a stud that extends from an interior portion of the fluid tank.
This locking function can be facilitated in a simple, practical and durable manner, for example, by providing a locking wedge on one of the sleeve and the stud, and a corresponding locking groove on the other of the sleeve and stud.
The dampening effect of the dampener assembly may be improved by attaching and stacking two or more dampener elements on top of each other. To increase the stability of the stacked dampener elements, junction points of each of the dampener elements may be designed as connector sockets, which connect the dampener elements together.
It should be appreciated that other methods of attaching the dampener assembly inside a fluid tank, as well as, other methods of attaching multiple dampener elements together may be considered. A simple alternative uses clips to connect the dampener elements to each other or to a fluid tank.